That's a problem for Drey, 74, whose house is about as old as she is. "I have old lamps, so (CFL bulbs) don't fit everywhere. But where they do fit, we have them in."
•Many CFL bulbs don't work well with dimmer switches and three-way light fixtures. A few will work, but they're hard to find. "If you put a regular CFL on a dimmer, in some cases it will hum and snap; it won't live as long, and it won't dim," Horowitz says.
When used with a dimmer switch, CFL bulbs typically will dim to about 20 percent of their full intensity and then cut out. They also must be turned on at a high setting and then dimmed, says Philip Scarbro, consumer division director at Energy Federation Incorporated, a group that promotes conservation.
When used in a three-way light fixture, many CFL bulbs will pop, hiss and buzz. There are a few three-way CFL bulbs, but they're tough to find and so big they do not fit in many lamps. Such bulbs often come with adaptors to lengthen the lamp's harp so the bulb will fit.
•They're still not widely available. Most supermarkets carry a limited supply of CFL bulbs. For more variety, buyers must go to a hardware store or a larger retailer such as Home Depot or Wal-Mart. Some have begun ordering fluorescent bulbs online, from websites such as bulborama.com and eft.org.
For many consumers, the reluctance to use CFLs comes down to the dingy light they can emit and questions about their safety.
CFLs give off a different color of light than incandescent bulbs. A measure of that is the color rendering index (CRI), which indicates how "true" colors will look. A CRI of 100 is sunlight or an incandescent bulb. Most CFLs are rated in the 80s, Scarbro says.
That's close enough to an incandescent light that many people won't notice, says Bill Burke, an architect who teaches builders how to use fluorescent lighting at Pacific Gas and Electric's Pacific Energy Center in San Francisco.
But it's not close enough for amateur photographer Eric Chan of Belmont, Mass.
"I don't like the quality" of CFL bulbs, Chan says. "As a photographer who produces my own color prints, I am unusually picky about how these prints ought to look. They look fine under daylight, incandescent and halogen bulbs but appear mediocre in comparison when lit by CFL bulbs."
CFLs are significantly brighter than the fluorescent lights used in schools and offices during the 1960s and 1970s. Those lights typically have a CRI rating of about 25.
Today, companies such as GE and Philips are starting to market what they call "natural" or "full spectrum" CFLs. They're closer to incandescent but not quite as bright.
CFL bulbs are best in table or floor lamps with a shade, Samla says. "They have such good colors now that you can't tell."
Unlike incandescent bulbs, however, compact fluorescents can pose a health hazard. CFL bulbs usually contain 3 to 5 milligrams of mercury, although new types have as little as 1 to 2 milligrams. Mercury is a toxin that can be particularly dangerous to children and fetuses.
There's no danger in using CFL bulbs, but if they break, users should don plastic gloves and take steps to avoid contamination.
If a CFL breaks, stay calm, Scarbro says. It's not quite a hazardous-material situation: The amount of mercury in a CFL bulb is tiny compared with older thermometers used to measure temperatures, which had about 400 milligrams.